He read once that love is not an emotion or a state of being, but a process: a continuous, never-ending negotiation of feelings and circumstance. One could learn to love just as one could learn to ride a bike: with lots of bumps and bruises along the way.

It's hard to determine exactly which was his Ifirst/I kiss; or rather, what should count as his first Iproper/I kiss.

The first non-family kiss he can remember was Jenny Taylor in Kindergarten. She had white blonde hair and big blue eyes and a laugh like a silver bell. He chased her around the play park, giggling and panting, until finally he had her cornered by the playhouse. "I caught you!" he announces, triumphant, but still unsure what to do with his captive.

She pretends to be scared, but her china blue eyes are laughing. "Now you have to kiss me!"

Before he can decide if this is a fair punishment, she presses her coral pink mouth, sticky with sweets, against his dry, chapped lips. Her laughing eyes meet his shocked expression, and she's off again with a giggle: "Can't catch me!"

Oh, but he can try!

His first Amy kiss comes when they are eight years old. They're playing Raggedy Doctor, of course, and the Doctor has to kiss Amy to wake her up from the deadly alien coma.

It's Sleeping Beauty mixed with ICasualty/I, but who is he to complain?

He even gets to give it a second go when he doesn't get it right the first time.

His first snog comes at Jeff's thirteenth birthday party, but he'd really rather not count that one, because that would mean his first grown-up kiss was with someone other than Amy.

He'd spun the bottle, and it landed on Cheris Blackwell. Then Cheris spun, and it landed back on Rory, so they Ihad/I to kiss with tongues.

His first snog with Amy was less than a week later, when she decided they needed to "practice". She'd kissed Jeff and Colin at the party, and apparently there was a rumor going around that she was a less than impressive kisser.

Rory wasn't sure how they could tell from the chaste pecks they'd planted on her at the party. If he'd had telekinetic powers he could have set the house on fire with the intense stare he gave the bottle when Amy was spinning; he was relieved to see they were as shy and nervous as he was, and eager to get it over with as quickly as possible. He couldn't stand to see Amy kissing other boys the way Cheris had kissed him.

Amy was already the prettiest girl in their school, and the object of many fantasies. Jeff and Colin should have been the envy of every other boy, getting to snog Amy; of course, what they did could hardly count as a "snog". Saying she was rubbish was more than likely the other boys' way of covering up their failure to capitalize on the situation. Rory Icould/I tell Amy that, and maybe she'd feel a little better…but then again, practice Idoes/I make perfect, and neither of them have much experience with kissing!

Their first attempt barely gets off the ground. Amy lunged in like a hawk striking at a field mouse, and Rory tilted his head the wrong way, and the end result was her forehead making a crash landing on his nose.

He waves off her concern, pushing down the pain and preparing for a second try. This time Amy takes it more slowly, afraid to wound him again, but now it's her hesitancy that's working against them. She tilts her head one way, he tilts his another; she finally makes contact, but completely misses his mouth.

She's getting frustrated, but she's still determined. Afraid he'll wind up with a bloody nose, Rory reaches out to still her. Cradling her face in his hands, he closes the distance between them in a heartbeat. Her lips are warm and slippery with a sweet-tasting lip-gloss, and when he reaches out for a proper taste, the tip of her tongue meets his in a slow, careful caress.

He can barely see for the fireworks exploding around the edges of his vision. When the room stops spinning, he notices her skin looks as flushed as his feels. "Rubbish?" she asks.

Around the lump in his throat, he's able to answer: "Definitely not."

This is the kiss he'd like to remember as his first.

The road to sex is long and winding, full of agonizing detours and thrilling milestones. Amy accounts for a lot of both.

He doesn't get to call her his girlfriend until they're well out of school, and in the meantime he does try to date other girls.

When he's fifteen, there's Amanda. Short, brunette, and bespectacled, she lives next door to his grandmother, and one summer vacation he's shocked to discover she actually has a crush on him. They go for walks in the fields surrounding the village and kiss and fumble around under an ancient oak tree next to a sheep pasture. For the first time, he touches a breast.

It ends when Amy comes back from visiting an elderly aunt to claim her best friend. He runs to her side without a second thought. It's not until one of Amanda's friends throws a Coke in his face at the arcade that he even realizes what he's done.

Amy starts dating an older boy from a bigger town, and Rory starts spending time with Kate Marling. She's cute in a bookish way, and she actually laughs at his jokes, and for a while he doesn't even notice that Amy doesn't have any time to spend with him.

One night he and Kate dress up nice and go out to a restaurant with tablecloths and candles, and afterwards Rory receives his first hand job. He drops her off at her door and walks home on a cloud. When he gets there, Amy is waiting for him.

She's broken up with her latest bloke, and has come to her best friend for some cheering up. Fortunately she's more angry than upset; Rory doesn't know what to do with her when she's crying. Fortunately, that's not often.

She's brought along a flask filled with little sips of different liquors from her aunt's stash. They wash the foul-tasting blend down with orange squash and a packet of crisps, and play a complicated drinking game with cards that Amy can't quite remember the rules to. Amy gets giggly and sleepy, and his head feels light and fuzzy, so he's not quite thinking when she leans over to kiss him.

Nor is he thinking when she pulls him to his bed and starts taking off his clothes. His synapses start to fire when she reaches into his trousers, and his brain is screaming at him by the time she's managed to unhook her bra. Still, he doesn't really figure out exactly what is going to happen until all their clothes are shed and she's pulling him down on top of her. "It's my first time…" she whispers, and thank God his brain has warmed up enough not to laugh at the absurdity of it all.

The last thing she says before drifting off to sleep is, "I hope this doesn't ruin our friendship."

Still, he does his best to let Kate down easy. He doesn't blame her for slapping him.

The next time he gets to have sex is more than a year later when he meets Aislinn. She's going to be attending the same nursing school he is after he graduates, and they meet during an Open Day. She asks for his number and calls him to go see a film and next thing he knows he's in love for the first time. Well, that is: he's in Irequited/I love for the first time.

They make it through the school year and start their nursing course together. Amy says she's happy for him, she likes Aislinn, and they go on double dates with whichever guy Amy's seeing at the time. Everything is perfect until the summer when Aislinn goes away on a six-week volunteer trip to Africa.

Amy and Rory spend most days together. She isn't seeing anyone, and Rory can't remember a time when his life didn't revolve around Amy or, more recently, Aislinn.

One tipsy night after the pub Amy pulls him into a dark alley between shops and starts snogging him senseless. He pulls away, and she pouts, confused. She tries again, and he puts a hand out to stop her. He can't bring himself to actually tell her no, but still: he can't do this to Aislinn. She deserves better.

Amy can read the determination in his eyes. For a moment she's shocked: he's never refused her before! But she recovers quickly, laughing it off like it was a joke all along, and pulls him back out onto the lane. In minutes, it's as if nothing's happened.

When Aislinn comes back she tells Rory she's leaving him for some Swedish doctor she worked with in Africa. Amy buys him a night of rounds and tells him he's better off, he's too good for her, and she never liked that other girl anyway.

Soon they're spending most days together just like they used to, only now there's more kissing and a lot more sex. He starts to wonder if he can finally call himself her boyfriend. When her Raggedy Doctor comes back, he finds out he can't.

There are advantages to being the boring, dependable one, if you have the patience: Rory has the patience. Amy cries on his shoulder, and rages into his pillow, and for weeks she alternates between swearing she never wants to hear the name "Doctor" again and talking about nothing else. She's resilient, though, and soon she's smiling and laughing again, and things are the way they always were, but better.

Rory doesn't know if they're falling in love, or just starting to realize they already have.

She agrees to marry him. She runs off with her not-so-imaginary friend. Rory is kidnapped from his stag do. He dies, he's resurrected; Amy dies, and then she's resurrected (2,000 years later; he's with her every minute).

The universe is re-built from scratch.

Their heads are a jumbled-up mess of memory and timelines Stephen Hawking would have difficulty wrapping his head around.

Some things are still the same. Some things could never be changed. It's all there, still plugged into his brain, each and every lesson he's learned: the kisses, the laughter, the pretty blue eyes and the shy, awkward smiles. The disappointments, the triumphs: the hearts that he broke and the ones that broke his in return.

They're all real, and they all lead him here: to his honeymoon and the happiest time of his life. To his radiant, giggling bride who is jumping up and down on their hotel bed in her wedding dress. To the night ahead that they will share, just the two of them, before they rejoin their alien tour guide to travel the universe, righting wrongs and vanquishing foes. Before they are time travelers, heroes, and companions to a madman, they'll spend this night as Amy and Rory, two very human beings whose hearts passed many trials to learn to beat in synch.

Amy dismounts from the bed, her skirts flying as she leaps into his arms. "Ready, lover?" she asks, breathless.

"Ready."